(a)[2]
The mammalian circulatory system is known as a closed double circulation. Explain why it is called a closed circulation and why it is called a double circulation.
(b(i))[3]
Name structures 1, 2 and 3, as indicated in Fig. 5.2.
(b(ii))[3]
Explain why the wall of chamber Y is thicker than the wall of chamber X, as shown in Fig. 5.3.
(c)[4]
Describe how the contractions of the chambers of the heart are coordinated during one cardiac cycle.